According to the research, about 75% of the fuel consumption is related to the vehicle mass, reducing the vehicle mass can effectively reduce the fuel consumption and emissions. It is one of the important ways to choose lighter material as far as possible under the requirement of ensuring the strength and stiffness of auto parts. Magnesium alloys are the lightest metal structural materials in common use and are abundant, making them the material of choice for automotive weight reduction to improve fuel economy and maneuverability.

At present, the instrument panel crossbeam of automobile is usually welded with steel pipe and steel plate stamping parts. The number of components of this kind of steel instrument panel crossbeam assembly requires welding and assembly, which is not conducive to size control, and the overall weight is large, which does not conform to the concept of lightweight. Using magnesium alloy die casting instrument panel beam can reduce the weight by more than 50%, the lightweight effect is very obvious. The main reason is that magnesium alloy is the lightest metal structure material in the present application, which has the advantages of low density, high specific strength and specific stiffness, good damping, machinability and casting performance, so magnesium alloy instrument panel beam is widely used in foreign automotive products. The GM G-Van uses a dashboard base with a mass of 15kg, probably the largest in use today. In addition, some cars of Mercedes, Chrysler, Fiat and so on use magnesium alloy integral panel base (instrument panel).

Compared with steel instrument panel, magnesium alloy instrument panel beam has the following characteristics:

(1) The density of lightweight magnesium alloy is 1.78g/cm3, which is only 1/4 of the density of steel, and the weight reduction is more than 50%.

(2) High integration degree of parts, size stability compared with steel parts, magnesium alloy instrument panel beam adopts integral die casting production process, which can integrate more than 20 parts of traditional steel CCB into one piece.

(3) The installation of high dimensional accuracy due to the use of integral die casting, high dimensional accuracy, all dimensional tolerances can be controlled within 0.5mm, to solve the current steel skeleton installation process interference and abnormal sound and other problems.

(4) Flexible design due to the use of die casting process, product technology is good, part shape design freedom.

(5) Green environmental protection magnesium alloy materials can be 100 percent recycled.

Selection of magnesium alloy

At present, there are many kinds of magnesium alloys. The automobile industry mostly uses AM and AZ alloys, and the commonly used magnesium alloys are mainly AM60B and AZ91D. The aluminum content of AM60B is lower, because with the decrease of aluminum content, the toughness of the material gradually increases, so compared with AZ91D, AM60B has better toughness and plasticity. AM60B is a high purity grade, so it has the same excellent corrosion resistance as AZ91D, and better corrosion resistance than A380 aluminum alloy.

CAE analysis

There are many accessories on the crossbeam of the instrument panel, resulting in complex forces and different directions, so it is necessary to analyze according to different accessories and different states.

According to the force condition and CAE analysis requirements, the grid graph of the instrument panel beam was made (see FIG. 1) and six aspects of beam stiffness, knee load and side impact load were analyzed, and the equivalent stress distribution of the instrument panel beam under a given working condition was obtained. The results show that the stress concentration mainly appears in some bolt fulcrum of the installation instrument, and the stress value is small and evenly distributed in other parts due to the low degree of load (see Figure 2). The analysis results of the whole piece show that the instrument panel beam made of AM60B magnesium alloy material fully meets the performance requirements of the given parts and components, and meets the service conditions (see Table 2).

In the early stage of magnesium alloy parts, metal mould gravity casting was adopted. It was found that due to the low melting point and density of magnesium alloy, most of the alloys had good fluidity and low specific heat capacity, and it was easy to obtain high cooling rate. Therefore, ideal castings could be obtained under moderate pressure. According to relevant reports, the magnesium alloy instrument panel crossbeam of a certain Audi model was successfully die-cast on a cold chamber die casting machine equipped with an automatic pouring mechanism with clamping force of 24.5MN. Therefore, it is completely feasible to adopt cold chamber die casting for the magnesium alloy instrument panel crossbeam introduced in this paper.

                                                                        3000T cold chamber die casting machine

According to the structural performance requirements of the instrument panel beam, combined with the characteristics that the fatigue performance of AM60B is very sensitive to the internal defects, the die casting process of the instrument panel beam is required to fill smoothly, achieve sequential solidification and avoid the occurrence of various casting defects. In this way, the casting with fewer defects and high quality can be obtained, and the production efficiency can be improved, which also lays a technological foundation for the application of new materials in the instrument panel beam.

Taishan Zhongmei technology produces dashboards that are used by Ford, Land Rover, etc., in their vehicles.

Material: Magnesium alloy AZ91D

Size:700*220*86mm

Weight:0.82kg

Die casting machine:900T High Pressure Cold Chamber die casting mahcine

Taishan Zhongmei Technology Co., Ltd. is a Chinese company specializing in the research, development and application of magnesium alloy and aluminum alloy materials and products, providing precision parts of magnesium alloy/aluminum alloy high-pressure casting, semi-solid die-casting and liquid die forging for automotive customers. It covers an area of 120,000 kilosquare, with a total investment of 0.2 billion dollars and 400 employees. It is a new material and new energy enterprise. We had pass high-tech enterprise IATF16949:2016 Automotive management system certificate.

China’s abundant magnesium reserves account for more than 70% of the world’s total magnesium resources, including 27% magnesite, ranking first in the world. The development of magnesium alloy industry in China is in line with China’s resource strategy, the world’s demand for magnesium alloy, more competitive prices, and the industrial advantages of supporting facilities for magnesium alloy production. China Magnesium Company is located in Taishan, Guangdong Province, China, near Shenzhen port and Hong Kong, with lower transportation cost and logistics efficiency.

The magnesium ingot used by Zhongmei Technology Co., Ltd. is of high purity and complies with the standard Chinese magnesium alloy. In the process of production, the nozzle and waste are not reused to improve the purity of products, so that the performance of die-casting products is more stable.

To collaborate or know more, send an email to: corrine@zhongmei-tech.com.